FAQ

What is x402?

x402 is an open payment protocol for HTTP APIs. Instead of API keys, your client sends a small on-chain USDC payment with each request. No account, no subscription.

Do I need to sign up?

No. No account, no API key, no email. Just a wallet with USDC on Base.

What wallet do I need?

Any EVM wallet with USDC on Base, used through an x402 v2 client such as @x402/fetch with a viem account.

Is there a testnet endpoint?

No. The paid endpoint accepts Base mainnet USDC only. Use /demo/snapshot (free, canned result) to test your integration.

Does it work with x402 v1 clients?

No. Use an x402 v2 client. v1 clients cannot read the payment requirements, which are sent in the PAYMENT-REQUIRED header.

What does the snapshot check?

HTTP response headers: HSTS, CSP, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, Permissions-Policy. Plus presence of security.txt, robots.txt, sitemap.xml.

Does it run JavaScript or render the page?

No. It performs a plain HTTP GET and inspects the response headers only. No browser, no JavaScript execution.

Can I scan private or internal URLs?

No. The API only scans publicly reachable URLs over HTTP/HTTPS. Private IPs, localhost, and internal hostnames are rejected.

Is the result deterministic?

Yes. The same URL at the same point in time will return the same result. There is no AI scoring, no opaque logic.

What is the rate limit?

No artificial rate limit. Each call requires payment, which is the natural rate control.

I found a bug or have a question.

See Support.